Two Super-Earths found orbiting a star just 111 light years away
Researchers reveal little known exoplanet could well be a scaled-up version of Earth, and discover another of similar conditions in the process.
Two “super-earths” have been found orbiting a red-dwarf star just 111 light years away. The first planet called K2-18b was discovered in 2015, and was considered an ideal candidate to contain liquid surface water, a crucial requirement to host life as we know it.
The researchers used data from the High Accuracy Radial Velocity Planet Searcher (HARPS) using the telescope at La Silla Observatory, in Chile. The HARPS instrument allows quantifying the radial velocities of stars as well as detecting minor planets orbiting those stars.
When K2-18b was found, researchers first had to figure out the planet’s mass in order to verify whether it was mostly rock, and therefore a “Super-Earth”, or mostly gas, in which case it would be regarded as a scaled-down version of Neptune.
"If you can get the mass and radius, you can measure the bulk density of the planet and that can tell you what the bulk of the planet is made of," says Cloutier.
Cloutier and his team were able to determine the planet is either mainly rocky with a small gaseous atmosphere like earth, or predominantly water with a thick layer of ice on top.
With current data, they were unable to discriminate between both possibilities, but with the James Webb Space Telescope (JWST), which will be launched in 2019 they will be able to probe the atmosphere and examine the planet further.
Discovering K2-18C, the second Super-Earth
While looking through the data of K2-18b, Cloutier noticed an uncommon signal every nine days. In order to find out was it was, Cloutier collaborated with international teams of researchers from the Observatoire Astronomique de l’Universite de Geneve, the Institute of exoplanets (iREx), Univeriste de Grenoble, U of T Scarborough, and Universidade do Porto.
They found the signal did in fact come from another planet, which also appeared to meet the conditions of a Super-Earth, although it’s very close to its Star and possibly too hot to be deemed habitable.
The James Webb Space Telescope (JWST) will help further the investigation of these two Super-Earths in 2019.